Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764740AbZDJB3o (ORCPT ); Thu, 9 Apr 2009 21:29:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765995AbZDJB3X (ORCPT ); Thu, 9 Apr 2009 21:29:23 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:45441 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932333AbZDJB3V (ORCPT ); Thu, 9 Apr 2009 21:29:21 -0400 To: Gary Hade Cc: mingo@elte.hu, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, lcm@us.ibm.com References: <20090408210735.GD11159@us.ibm.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: Thu, 09 Apr 2009 18:29:10 -0700 In-Reply-To: <20090408210735.GD11159@us.ibm.com> (Gary Hade's message of "Wed\, 8 Apr 2009 14\:07\:35 -0700") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=67.169.126.145;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 67.169.126.145 X-SA-Exim-Rcpt-To: garyhade@us.ibm.com, lcm@us.ibm.com, linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, mingo@elte.hu X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Gary Hade X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 XM_SPF_Neutral SPF-Neutral * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay Subject: Re: [PATCH 2/3] [BUGFIX] x86/x86_64: fix CPU offlining triggered inactive device IRQ interrruption X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1508 Lines: 34 Gary Hade writes: > Impact: Eliminates a race that can leave the system in an > unusable state > > During rapid offlining of multiple CPUs there is a chance > that an IRQ affinity move destination CPU will be offlined > before the IRQ affinity move initiated during the offlining > of a previous CPU completes. This can happen when the device > is not very active and thus fails to generate the IRQ that is > needed to complete the IRQ affinity move before the move > destination CPU is offlined. When this happens there is an > -EBUSY return from __assign_irq_vector() during the offlining > of the IRQ move destination CPU which prevents initiation of > a new IRQ affinity move operation to an online CPU. This > leaves the IRQ affinity set to an offlined CPU. > > I have been able to reproduce the problem on some of our > systems using the following script. When the system is idle > the problem often reproduces during the first CPU offlining > sequence. You appear to be focusing on the IBM x460 and x3835. Can you describe what kind of interrupt setup you are running. You may be the first person to actually hit the problems with cpu offlining and irq migration that have theoretically been present for a long. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/